U.S. patent number 4,849,773 [Application Number 07/092,106] was granted by the patent office on 1989-07-18 for ink jet recording apparatus.
This patent grant is currently assigned to Seiko Epson Corporation, A Japanese Corporation. Invention is credited to Akio Owatari.
United States Patent |
4,849,773 |
Owatari |
July 18, 1989 |
Ink jet recording apparatus
Abstract
A liquid ink composition having a sodium ion concentration
between about 0.001 and 0.2% by weight or ink tank formed of resin
or synthetic rubber containing between about 10 and 100 ppm of
fatty acid or fatty acid derivatives is provided. The liquid
composition is useful in every ink tank formed of resin or
synthetic rubber containing fatty acid or the derivatives. The ink
tank is also useful in despite of sodium ion concentration of ink.
Formation of insoluble substances produced to react with sodium ion
and fatty acid or the derivatives deteriorates the ink flow to clog
the filter in the pass. The low sodium ion concentration of ink, or
the low fatty acid or the derivatives concentrations of tank
material prevents from forming the insoluble substances.
Inventors: |
Owatari; Akio (Nagano,
JP) |
Assignee: |
Seiko Epson Corporation, A Japanese
Corporation (Tokyo, JP)
|
Family
ID: |
16570948 |
Appl.
No.: |
07/092,106 |
Filed: |
September 2, 1987 |
Foreign Application Priority Data
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Sep 5, 1986 [JP] |
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61-209317 |
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Current U.S.
Class: |
347/100;
106/31.27; 524/322 |
Current CPC
Class: |
B41J
2/175 (20130101); C09D 11/30 (20130101) |
Current International
Class: |
B41J
2/175 (20060101); C09D 11/00 (20060101); G01D
015/16 () |
Field of
Search: |
;346/1.1,140,75
;106/22,23,20 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2930491 |
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Feb 1981 |
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DE |
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3117943 |
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Feb 1982 |
|
DE |
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3322502 |
|
Jun 1983 |
|
DE |
|
3344978 |
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Dec 1983 |
|
DE |
|
3412426 |
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Oct 1984 |
|
DE |
|
202358 |
|
Jun 1981 |
|
JP |
|
222163 |
|
Jun 1982 |
|
JP |
|
Primary Examiner: Hartary; Joseph W.
Attorney, Agent or Firm: Kaplan; Blum
Claims
What is claimed is:
1. An ink jet recording apparatus comprising an ink tank having an
acqueous liquid ink stored therein, the ink tank formed of a resin
or synthetic rubber containing at least one fatty acid or fatty
acid derivative in an amount between about 10 and 100 ppm and the
ink is an aqueous ink having a sodium ion concentration between
about 0.001 and 0.2% by weight.
2. An ink jet recording apparatus comprising an ink tank having an
aqueous liquid ink with a sodium ion concentration between about
0.001 and 0.2% by weight stored therein wherein said ink tank is
formed of a resin or synthetic rubber obtained by polymerizing the
resin with a catalyst which has been neutralized by a fatty acid or
fatty acid derivative which remains in the tank material in an
amount less than the amount which causes formation of insoluble
substances in the ink by reaction of the sodium ions present in the
ink with the fatty acid or fatty acid derivative.
3. The ink jet recording apparatus of claim 2, wherein the resin or
synthetic rubber is selected from the group consisting of
polyolefin resin, polyvinyl chloride, polyvinylidene chloride,
silicon resin, ethylene vinyl acetate copolymer, ABS resin,
polyacetal, nylon, unsaturated polyester resin, polyethylene
terephthalate, aramid, styrene butadiene rubber, butadiene rubber,
chloroprene, nitryl rubber, butyl rubber, EPDM, urethane rubber,
silicon rubber, acrylic rubber, ethylchlorohydrin rubber and
fluorine rubber.
4. The ink jet recording apparatus of claim 2, wherein the fatty
acid is selected from the group consisting of stearic acid, behenic
acid, oleic acid and erucic acid.
5. The ink jet recording apparatus of claim 2, wherein the fatty
acid derivative is selected from the group consisting of stearic
acid (Ca, Al, Mg, Zn) salt, stearamide, behenic acid (Ca, Al, Mg,
Zn) salt, behenamide, oleic acid (Ca, Al, Mg, Zn) salt, oleamide,
erucic acid (Ca, Al, Mg, Zn) salt and erucamide.
6. The ink jet recording apparatus of claim 2, wherein the aqueous
ink further includes a water-soluble dye and a wetting agent.
7. The ink jet recording apparatus of claim 6, wherein the
water-soluble dye is present in an amount between abut 0.5 and 10%
by weight.
8. The ink jet recording apparatus of claim 6, wherein the wetting
agent is present in an amount between about 5 and 80% by
weight.
9. The ink jet recording apparatus of claim 6, wherein the dye is
selected from a direct dye, an acid dye and a basic dye.
10. An ink jet recording apparatus comprising an ink tank having a
liquid ink stored therein, said ink tank sealed by the application
of heat and formed of a resin or synthetic rubber containing
between about 10 and 100 ppm of at least one fatty acid or fatty
acid derivative.
11. The ink jet recording apparatus of 10, wherein the resin is
polyethylene.
12. The ink jet recording apparatus of 10, wherein the fatty acid
or fatty acid derivative is stearic acid calcium.
13. An ink jet recording apparatus comprising an ink tank formed of
a resin or synthetic rubber containing at least one fatty acid or
fatty acid derivative, the tank suitable for storing an aqueous ink
having a sodium ion concentration between about 0.001 and 0.2% by
weight and the fatty acid or fatty acid derivative is present in an
effective amount for preventing the formation of insoluble
substances from the reaction of sodium ions in the ink with the
fatty acid or fatty acid derivative.
Description
BACKGROUND OF THE INVENTION
This invention relates to liquid ink compositions for use in ink
jet recording apparatus and, in particular, to a liquid ink
composition having a reduced sodium ion concentration in order to
prevent insoluble particles from leaching into the ink from ink
pouches or tanks in which the ink is stored.
Conventional ink jet printers achieve quiet, high speed, high
quality color printing using a variety of ink droplet ejection
techniques including continuous ink jet ejection, impulse ink jet
ejection, thermal ink jet ejection and the like. The techniques
generally eject ink droplets from an extremely minute nozzle
orifice having a diameter between about 10 and 100 .mu.m. In order
to pass through the minute nozzle orifice or ink flow path the ink
must be clean and stable.
Ink is generally prepared in a clean room in order to minimize the
introduction of dust particles. Alternately, the prepared ink is
filtered through a membrane filter having a mesh size of 1 .mu.m or
less. In addition, tanks for storing ink are cleaned with ultrapure
water using a precision cleaning process prior to being filled.
In conventional ink tank systems having a liquid ink stored
therein, the ink is clean only when it is first introduced into the
tank. After a period of time, at least in part due to changes in
environment, including temperature, the composition of the ink
deteriorates as a result of elution of material from the ink tank
into the ink. This material reacts chemically with the ink
composition to form insoluble substances and these insoluble
substances clog the minute paths, filters, orifices, nozzles and
the like of the ink jet printer. Consequently, ink flow is
interrupted and print quality deteriorates resulting in a dot
missing.
It is, therefore, desirable to provide an ink composition wherein
insoluble substances are not produced when the ink is stored in an
ink tank for an extended period of time.
SUMMARY OF THE INVENTION
Generally speaking, in accordance with the invention, a liquid ink
composition having a sodium ion concentration between about 0.001
and 0.2% by weight is provided. The ink composition includes at
least water, a soluble dye and a wetting agent. The liquid ink
composition is particularly useful in ink tanks formed of resin or
synthetic rubber containing between about 10 and 100 ppm of fatty
acids or fatty acid derivatives. Formation of insoluble substances
from the fatty acids or fatty acid derivatives in the ink tank is
avoided as a result of the low sodium ion concentration of the
ink.
Accordingly, it is an object of the invention to provide an ink
composition wherein insoluble substances are not produced when the
ink is maintained in an ink tank over an extended period of
time.
Another object of the invention is to provide a liquid ink
composition having a sodium ion concentration between about 0.001
and 0.2% by weight.
A further object of the invention is to provide an ink jet
recording apparatus having a resin or synthetic rubber ink tank
including a fatty acid or fatty acid derivative and having a liquid
ink such that chemical changes due to leaching of material from the
ink tank into the ink and formation of insoluble substances which
would cause deterioration of print quality are prevented.
Still other objects and advantages of the invention will in part be
obvious and will in part be apparent from the specification.
The invention accordingly comprises a composition of matter
possessing the characteristics, properties, and the relation of
components which will be exemplified in the composition hereinafter
described, and the scope of the invention will be indicated in the
claims.
DESCRIPTION OF THE DRAWINGS
For a fuller understanding of the invention, reference is had to
the following description taken in connection with the accompanying
drawings, in which:
FIG. 1A is a partial cross-sectional elevational view of the ink
supply system of an ink jet printer of the type used in accordance
with the invention;
FIG. 1B is a partial cross-sectional elevational view of an
alternate ink supply system of a typical ink jet printer; and
FIG. 2 is a partial cross-sectional elevational view of a further
alternate ink supply system having an integrally formed printhead
and ink tank.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1A shows a typical ink supply system 10 of an ink jet
recording apparatus. Ink supply system 10 contains an exchangable
ink tank 12 having a liquid ink composition 11 contained therein.
Ink composition 11 is supplied to a nozzle orifice 15 of a
printhead 14 through an ink supply tube 13 connected at one end to
ink tank 12 and at the other end to printhead 14. When ink supply
tank 12 is empty, ink supply tank 12 is detached from ink supply
tube 13 and replaced with a full ink tank 12. FIG. 1B shows an
alternate ink supply system 18. Ink supply system 18 is the same as
ink supply system 10 of FIG. 1A except that a filter 16 is provided
in ink supply tube 13 to prevent foreign matter or insoluble
particles such as dust from flowing to printhead 14. The use of
filter 16 improves the reliability of ink supply system 18 over the
reliability of ink supply system 10.
FIG. 2 shows a further alternate ink supply system 20 wherein
nozzle orifice 15 of printhead 14 is supplied directly with ink 11
from a unitary formed ink tank 21 having an ink composition 11
contained therein. This arrangement obviates the need for ink
supply tube 13.
The portions of the ink supply system that come into direct contact
with the ink must be made of materials that resist leaching into
the ink composition. These ink contacting portions are preferably
formed of resins such as polyolefin resin, polyvinyl chloride,
polyvinylidene chloride, silicon resin, ethylene vinyl acetate
copolymer, ABS resin, polyacetal, nylon, unsaturated polyester
resin, polyethylene terephthalate (PET), aramid and the like or
synthetic rubbers such as styrene butadiene rubber (SBR), butadiene
rubber, chloroprene, nitryl rubber, butyl rubber, EPDM, urethane
rubber, silicone rubber, acrylic rubber, epichlorohydrin rubber,
fluorine rubber and the like. These resins and synthetic rubbers
preferably contain appropriate amounts of assistants such as
stabilizers, UV absorption agents and anti-oxidants in effective
amounts for achieving their intended purposes.
In general, fatty acids or fatty acid derivatives contained in
resins or synthetic rubbers used to form ink tanks are eluted into
the ink composition and cause a chemical reaction that produces
insoluble substances. Specifically, when ink tank 12 containing ink
composition 11 was left standing for an extended period of time or
was maintained at an elevated temperature, fatty acids or fatty
acid derivatives contained in the resin or synthetic rubber of ink
tank 12 were eluted into ink composition 11. When the temperature
was reduced to normal room temperature, the eluted components
separated from the ink and insoluble sodium salts were formed as a
result of a chemical reaction between sodium ions in the ink and
the fatty acids or fatty acid derivatives. These insoluble sodium
salts clogged filter 16 and nozzle orifice 15 and interrupted ink
flow.
Sodium stearate having thread-like or needle-shaped crystals is
formed when the resin or synthetic rubber includes stearic acid,
stearic acid amide or stearic acid salts as additives. The sodium
stearate crystals cause filter 16 and any minute ink flow paths to
clog and ink flow to be interrupted. This phenomenon was especially
apparent when a resin or synthetic rubber ink tank having stearic
acid additives was maintained at an elevated temperature of greater
than about 40.degree. C. for a period of greater than one day. This
is presumably due to the fact that stearic acid, stearic acid amide
and stearic acid salts are soluble at elevated temperatures. In
addition, the polymer matrices of fat and synthetic rubber
oscillate at a molecular level resulting in elution of the stearic
acid and its derivatives into the ink. This phenomenon is even more
noticeable when the pH of the ink is raised.
The type or grade of resin or synthetic rubber determines the
amount of fatty acid and derivatives contained therein. In
particular, polyolefin resins such as polyethylene and
polypropylene are suitable for constructing ink tanks because they
are resistant to chemical degradation, relatively inexpensive and
easy to form in the shape of a bag. The fatty acid and derivatives
are added as stabilizers when the resin is polymerized or as slip
agents to prevent adhesion to a roller when the resin is formed as
a film.
In general, the fatty acid and fatty acid derivatives used have
between about 8 and 22 carbon atoms. Suitable fatty acids and fatty
acid derivatives include stearic acid, stearic acid salts such as
stearic acid calcium, stearic acid aluminum, stearic acid magnesium
and stearic acid zinc (stearic acid (Ca, Al, Mg, Zn)), stearamide,
behenic acid, behenic acid (Ca, Al, Mg, Zn), behenamide, oleic
acid, oleic acid (Ca, Al, Mg, Zn), oleamide, erucic acid, erucic
acid (Ca, Al, Mg, Zn), erucamide and the like. The type of
polyethylene film depends on the degree of polymerization of the
polyethylene and includes linear low density polyethylene (LLDPE),
middle density polyethylene (MDPE) and high density polyethylene
(HDPE). The amount of fatty acid and fatty acid derivative added
depends on the polyethylene type. Ink tanks containing fatty acids
and fatty acid derivatives can also be formed of vinyl chloride,
nylon, polyacetal, ethylene vinyl acetate, ABS resin and nearly all
synthetic rubbers.
Ink for ink jet printers must also be easy to handle in order to
prevent clogging of the nozzle orifice due to drying. The ink
preferably has a low viscosity so that it can be ejected as ink
droplets from an ink jet head with high response speed. Water-based
inks are generally used in ink jet printers and the compositions
generally contain water-soluble dyestuff components such as direct
dye, acid dye and basic dye as well as wetting components which
prevent ink from drying when the water evaporates. Direct dyes
usually contain a large amount of sulfonic acid sodium salt to
increase their solubility in water. In addition, sodium chloride is
used in salting-out processes, nitrous acid sodium salt is used in
diazo processes and sodium acetate, sodium carbonate, sodium
hydroxide and sodium sulfite are contained in the dye. As a result,
sodium ions in the ink cause fatty acids and fatty acid derivatives
contained in the ink tank material to be eluted into the ink as a
result of temperature changes and the like. The eluted components
cause formation of insoluble sodium salts of fatty acids and fatty
acid derivatives which prevent ink flow.
Aqueous solutions having varied sodium ion concentrations and
containing 1% potassium hydroxide (KOH) for the purpose of
accelerating elution of fatty acids and fatty acid derivatives were
poured into bags formed of low density polyethylene film, a
commonly used polyolefin resin. The thickness of the polyethylene
bags was 60 .mu.m and the sodium ion concentrations were 0.1, 0.15,
0.2, 0.25 and 0.3% by weight of sodium ions respectively. The bags
were heat sealed in a liquid to remove air bubbles and maintained
for 10 days at a temperature of 70.degree. C. Then the bags were
maintained at room temperature for an additional 5 days and the
products were observed. Thread-shaped crystals were observed in the
bags containing 0.25 and 0.3% by weight sodium ion. Analysis of the
solutions using an infrared spectrophotometer and X-ray
microanalyzer showed that the thread-shaped crystals were sodium
stearate. In the bags containing 0.1, 0.15 and 0.2% by weight of
sodium ions, no thread-shaped crystals were observed. It can
therefore be seen that even when fatty acids or fatty acid
derivatives were contained in the resin or synthetic rubber forming
the ink tank, insoluble sodium salts of the fatty acids or fatty
acid derivatives which would prevent ink flow were not formed when
the sodium ion concentration was 0.2% by weight or less.
When the sodium ion concentration in the ink was too low, dyes
associated in solution and the ink was unstable when it was
continuously ejected. Accordingly, the concentration of sodium ions
in an ink containing primarily water, a water-soluble dye and a
wetting agent should be between about 0.001 and 0.2% by weight. The
sodium ion concentration can be decreased to this level by using
ultrapure water which can be obtained by conventional methods such
as treatment of tap water using a reverse osmosis film and an ion
exchange resin.
In general, water-soluble dyes contain a heavy concentration of
sodium ions. This is due to use of sodium chloride in salting-out
processes, nitrous acid sodium salts in diazo processes and sodium
acetate, sodium carbonate, sodium hydroxide and sodium sulfate in
other processes. In addition, water-soluble dyes themselves can
contain sulfonic acid sodium salts. Nearly all water-soluble dyes
contain greater than about 5% sodium. The concentration of sodium
ions can be reduced by reducing the use of sodium in manufacturing
processes and replacing it with alkali metal compounds such as
potassium chloride and the like. Additionally, even when sodium
compounds are used, the number of sodium ions can be reduced by
filtering the dye solution through a strong acid cation exchange
resin deformed as an H-type such as Amberlite 120 series
(manufactured by Orugano Kabushiki Kaisha), Dowex 50W (manufactured
by Dow Chemical) and the like.
Direct dyes, acid dyes and basic dyes which appear in Color Index
can be used as water-soluble dyes in the ink composition of the
invention. The desired sodium ion concentration can be achieved by
using a manufacturing method that uses a reduced amount of sodium
or by purifying the ink composition after preparation. Since the
dye serves as the coloring material of the recording ink,
sufficient contrast must be maintained when the ink composition is
printed on a printing medium. On the other hand, the nozzles of an
ink jet head clog due to separation when water evaporates if the
dye density is too high. Between about 0.5 and 10% by weight of dye
is considered optimum.
A wetting agent is essential for preventing the ink from drying in
the nozzle of an ink jet head. Wetting agents include soluble
organic solvents such as polyhydric alcohols, ether derivatives and
ester derivatives of polyhydric alcohols, water-soluble amines and
cyclic compounds containing nitrogen. Specifically, polyhydric
alcohols include ethylene glycol, diethylene glycol, triethylene
glycol, propylene glycol, polyethylene glycol, glycerine, alkyl
ether derivatives of polyhydric alcohols such as ethylene glycol
monomethyl ether, diethylene glycol monomethylether, diethylene
glycol monobutylether, diethylene glycol dimethylether, diethylene
glycol methylethylether, triethylene glycol monomethylether and the
like, ester derivatives of polyhydric alcohols such as ethylene
glycol monoethylether acetate, diethylene glycol monomethylether
acetate, glycerylmonoacetate, glycerdiacetate and the like,
water-soluble amines such as monoethanol amine, diethanol amine,
triethanol amine, polyoxyethyleneamine and the like and cyclic
compounds containing nitrogen such as N-methyl-2-pyrolidone and the
like.
None of these water-soluble organic solvents contain sodium ions so
it is unnecessary to purify these solvents. However, purification
should be carried out when water-soluble organic solvents which use
sodium compounds in the elaboration process are used. The
prevention of drying depends directly on the amount of organic
solvent added. However, the organic solvent increases the viscosity
of the ink and therefore it is not desirable to add too large an
amount.
In general, the ink droplet ejection cycle is affected by the ink
viscosity. When the ink viscosity is too high, the ejection cycle
does not increase proportionately and ejection properties become
unstable. An ink viscosity of 50 mPas or lower is desirable. This
is accomplished by preparing a composition containing between about
5 and 80% by weight of water-soluble organic solvent.
The pH value of the recording ink is adjusted to between about 12
and 14 to accelerate the osmosis to recording paper. This is
described in U.S. Pat. No. 4,352,691 of the named inventors herein.
The earlier application discloses that alkali metal hydroxide can
be used for increasing the pH value. However, it has now been
determined that lithium hydroxide and potassium hydroxide are
suitable but sodium hydroxide cannot be used.
Other ink additives such as antiseptics, mold inhibitors, chelating
agents, pH adjusters and the like can be added as necessary.
However, since many of these additives are sodium compounds, they
should be added in very small amounts. It has also been shown that
the production of insoluble substances was restrained even when
more than about 0.2% by weight of sodium ions were contained in the
ink when the amount of fatty acid and fatty acid derivatives in the
resins and synthetic rubbers was reduced.
One hundred cubic centimeters of an aqueous sodium solution having
a sodium ion concentration of 0.5% by weight in a 1% by weight KOH
solution was poured into polyethylene bags containing 5 ppm, 10
ppm, 50 ppm, 100 ppm and 200 ppm of stearic acid calcium. Each bag
was heat sealed in a liquid and maintained for 3 days at room
temperature. Each solution was filtered through a metallic filter
having a pore size of 10 .mu.m. Insoluble substances were produced
only in the bag of sodium chloride solution containing 200 ppm of
stearic acid calcium. The bag containing the 5 ppm solution
developed a leak along the heat seal. As can be seen, production of
insoluble substances was prevented independent of the percent by
weight of sodium ions when a polyethylene bag having a
concentration of stearic acid calcium between about 10 and 100 ppm
was used.
The invention will be better understood with reference to the
following examples. These examples are presented for purposes of
illustration only and are not intended to be construed in a
limiting sense.
EXAMPLE 1
An aqueous dye solution containing 10% by weight of C.I. Direct
Black 38 and 90% by weight of ultrapure water was prepared. 100 g
of the aqueous dye solution was passed through an ion exchange
column filled with an H-type strong acid cation exchange resin,
Amberlite 120B, in order to remove sodium ions. A refined aqueous
dye solution containing 10% by weight of C.I. Direct Black 38 was
obtained. In the refined aqueous dye solution the sodium was
substituted with hydrogen and the pH value was raised to pH 10
using a KOH solution. The following ink composition was prepared
using this refined aqueous dye solution:
______________________________________ Refined aqueous dye solution
12% by weight Glycerine 20% by weight Ultrapure water 68% by weight
______________________________________
Ion chromatography confirmed that the solution contained 0.1% by
weight of sodium, 0.4% by weight of potassium and 0.5% by weight of
chlorine.
The ink solution was filtered through a Milipore membrane filter
and degased. 150 g was poured into an ink bag formed of a
polyethylene film and heat sealed in a liquid to yield an ink tank.
The ink tank was maintained at a temperature of 70.degree. C. for
120 hours and then at room temperature for an additional 3 days.
The ink tank was connected to an IP-130K ink jet printer made by
Seiko Epson Kabushiki Kaisha having nylon filters with a pore size
of 30 .mu.m in the ink flow path. The filters were observed after
10 ink tanks had been used and they were not clogged.
COMPARATIVE EXAMPLE 1
A 10% aqueous dye solution containing 10% by weight of C.I. Direct
Black 38 was prepared as described in Example 1 but was not passed
through an ion exchange column and the pH was adjusted using the
same amount of KOH solution. Then an ink having the ink composition
of Example 1 was prepared using this aqueous dye solution. Ion
chromatography confirmed that the solution contained 0.5% by weight
sodium, 0.4% by weight of potassium and 0.5% by weight of
chlorine.
An ink tank was prepared and maintained in the same manner as
described in Example 1. The ink tank was used for printing and
deterioration in print quality was observed when the third ink tank
was used. Nearly all of the filters in the ink flow path were
clogged. As a result of observation with an infrared spectrometer
and an electron micrograph, it was confirmed that the filters were
clogged with sodium stearate crystals. Ink could not flow due to
the clogged filters and was not adequately supplied to the
recording head which caused the observed deterioration in print
quality.
EXAMPLE 2
C. I. Direct Black 154 was synthesized by coupling using a nitrous
acid sodium salt and by a second method wherein a sodium containing
compound was not used. The dye was separated using hydrochloric
acid and was dissolved in a KOH solution. Then the following ink
was prepared using a 10% aqueous solution of the dye solution:
______________________________________ Aqueous solution containing
10% by 15% by weight weight of C.I. Direct Black 154 Polyethylene
glycol #300 30% by weight Ultrapure water 55% by weight
______________________________________
Ion chromatography confirmed that the solution contained 0.03% by
weight sodium, 0.6% by weight potassium and 0.3% by weight
chlorine. An evaluation was conducted as described in Example 1 and
the filters in the ink flow path were not clogged. Good printing
quality was observed.
EXAMPLE 3
Dyes of Examples 3-1 to 3-8 were reduced as described in Example 1
and 2 and were used for preparing the inks of Examples 3-1 and 3-8.
For comparison, commercial dyes were prepared as inks 3-10 and
3-13. Sodium, potassium and chlorine were measured using ion
chromatography. The following Table shows the ink compositions.
TABLE 1 ______________________________________ Composition Wt %
Na.sup.+ K.sup.+ Cl.sup.- ______________________________________
Example No 3-1 C.I. Direct Black 154 2 0.18 0.7 0.5 Glycerine 15
Diethylene glycol 5 KOH 1 Ultrapure water 77 3-2 C.I. Direct Yellow
86 3 0.2 0.2 0.8 Triethylene glycol 28 Ultrapure water 68.99 EDTA -
2 sodium 0.01 3-3 C.I. Direct Blue 2.5 0.15 0.3 0.4 Polyethylene 12
glycol #400 Ethylene glycol 3 monomethylether Ultrapure water 82.3
Proxel XL-2 0.2 (a mold inhibitor manu- factured by Imperial
Chemical Industries) 3-4 C.I. Direct Red 39 2 0.05 0.2 0.4
Triethanol amine 15 Ultrapure water 82.9 Dehydro acetic acid 0.1
sodium salt (a mold inhibitor) 3-5 C.I. Acid Red 254 1.5 0.12 0.78
0.5 Glycerine 12 N--methyl-2-pyrolidone 4 KOH 1 Ultrapure water
81.5 3-6 C.I. Acid Yellow 23 4 0.1 0.3 0.6 Glycerine 20
Polyethylene glycol #200 2 Ultrapure water 73.9 Hokuside LX-2 0.1
(a mold inhibitor manu- factured by Hokko-Kagaku) 3-7 C.I. Basic
Violet 10 2 0.16 0.3 0.8 Diethylene glycol 10 Ethylene glycol 5
Ultrapure water 82.8 EDTA-2 sodium 0.1 Proxel XL-2 0.1 3-8 C.I.
Direct Black 75 3 0.1 0.4 0.6 Glycerine 5 Triethylene glycol 50
monomethylether Ultrapure water 41 KOH 1 com- parative Examples
3-10 C.I. Direct Black 154 2 0.4 0.7 0.5 Glycerine 15 Diethylene
glycol 5 KOH 1 Ultrapure water 77 3-11 C.I. Acid Red 254 1.5 0.5 0
0.4 Glycerine 12 N--methyl-2-pyrolidone 4 KOH 1 Ultrapure water
81.5 3-12 C.I. Acid Yellow 23 4 0.3 0 0.3 Glycerine 20 Polyethylene
glycol #200 2 Ultrapure water 73.9 Hokuside LX-2 0.1 (a mold
inhibitor, manu- factured by Hokko-Kagaku) 3-13 C.I. Basic Violet
10 2 0.8 0 0.9 Diethylene glycol 10 Ethylene glycol 5 Ultrapure
water 82.8 EDTA-2 sodium 0.1 Proxel XL-2 0.1
______________________________________
The results of evaluation of these inks in the manner described in
Example 1 is shown in Table 2.
TABLE 2 ______________________________________ Ink No. Printing
Test Clogging of filter ______________________________________ 3-1
3-2 Good print quality. 3-3 Quality equal to that obtained 3-4 when
the first ink tank was used None 3-5 was obtained when the tenth
tank 3-6 was used. 3-7 Printing conditions were 3-8 stably
maintained. ______________________________________
______________________________________ Comparative Examples
______________________________________ 3-10 Inferior printing was
observed Yes when the 3rd ink tank was used 3-11 Inferior printing
was observed Yes when the 3rd ink tank was used 3-12 Inferior
printing was observed Yes when the 5th ink tank was used 3-13
Inferior printing was observed Yes when the lst ink tank was used
______________________________________
As shown in Table 2, no clogging was observed when the sodium ion
concentration was 0.2% by weight or less. Clogging was not
influenced by the potassium or chlorine ion concentration.
EXAMPLE 4
A test was conducted as described in Example 1 except that the ink
tanks were replaced with tanks of material set forth in Table 3.
The inks of Example 1 and of Comparative Example 1 were used and
the results are also shown in Table III.
TABLE 3 ______________________________________ Ink of Ink of
Material Example 1 Comparative Example 1
______________________________________ Polypropylene .circle. X
Polyvinyl chloride .circle. X Nylon .circle. X NBR .circle. X Butyl
rubber .circle. X ______________________________________ .circle. =
Good printing was maintained through the 10th ink tank printing. X
= Inferior printing was observed before the 10th ink tank was used
and the filter was clogged.
When inks having 0.2% by weight or less of sodium ions were used,
the filters were not clogged. However, when the ink had a sodium
ion concentration of 0.5% by weight, the filter was clogged
irrespective of which tank was used.
EXAMPLE 5
The inks of Example 3-1 to 3-8 and Comparative Example 3-10 to 3-13
were poured into ink tanks of Examples 5-1 to 5-8 and Comparative
Examples 5-10 to 5-13. Each of the tanks was sealed, maintained at
a temperature of 70.degree. C. for 10 days and then maintained at
room temperature for an additional 3 days. Each ink tank was used
in an IP-130K ink jet printer made by Seiko Epson Kabushiki Kaisha
and having filters made of nylon mesh with an area of 3 cm.sup.2
and mesh openings of 30 .mu.m. Printing was carried out using all
150 cc of ink in each ink tank. Table 4 shows the materials used
for the ink tanks and Table 5 shows the results of observation of
the filter.
TABLE 4 ______________________________________ Ink Tank No.
Material of Ink Tank Ink ______________________________________ 5-1
Film of a blend of LDPE and 150cc of ink shown HDPE, having a
thickness in Example 3-1 of 60um 5-2 Film of polyvinyl chloride,
150cc of ink shown having a thickness of 30um in Example 3-2 5-3
Molded case of nylon 12 150cc of ink shown in Example 3-3 5-4
Ethylene vinyl acetate film 150cc of ink shown in Example 3-4 5-5
Molded case of polyacetal 150cc of ink shown in Example 3-5 5-6
Molded case of styrene 150cc of ink shown butadiene rubber in
Example 3-6 5-7 Molded case of nitryl rubber 150cc of ink shown in
Example 3-7 5-8 Molded case of EDPM 150cc of ink shown in Example
3-8 5-10 Material of 5-1 150cc of ink shown in Example 3-10 5-11
Material of 5-5 150cc of ink shown in Example 3-11 5-12 Material of
5-6 150cc of ink shown in Example 3-12 5-13 Material of 5-7 150cc
of ink shown in Example 3-13
______________________________________
TABLE 5 ______________________________________ Ink Tank No.
Condition of filter ______________________________________ 5-1 5-2
5-3 5-4 There were no sticky substances in any filters 5-5 5-6 5-7
5-8 5-10 The filter was clogged over the entire surface. 5-11
One-fifth of the surface of the filter was clogged. 5-12 The filter
was clogged over the entire surface. 5-13 The filter was clogged
over the entire surface. ______________________________________
No clogging was observed in the filters when the ink tanks of
Examples 5-1 to 5-8 were used. Any eluted components were small
enough to pass through the filter, thereby eliminating difficulties
due to filter clogging. When the ink tanks of Examples 5-10 to 5-13
were used, the filters were clogged with a filmy substance composed
of an aggregation of fibers. In addition, print quality
deteriorated. When an ink tank of the type used in Example 5-11 was
used continuously, the entire filter became clogged and print
quality deteriorated.
EXAMPLE 6
200 cc of ink having the following composition was prepared.
______________________________________ C.I. Direct Black 154 3 wt %
Polyethylene glycol #400 20 wt % Diethylene glycol 10 wt %
Ultrapure water 67 wt % ______________________________________
The ink composition was poured into a polyethylene bag containing
50 ppm of a fatty acid series stabilizer and a fatty acid series
slip agent. The bag was heat sealed in a liquid to remove air
bubbles. The ink tank was maintained at a temperature of 70.degree.
C. for 10 days and then maintained at room temperature for an
additional 3 days. The ink was used in an IP-130K ink jet printer
made by Seiko Epson Kabushiki Kaisha and printing was carried out.
The ink flow was not interrupted and when the nylon filter having a
pore size of 30 .mu.m used in the ink flow path of the printer was
examined after 200 cc of ink was consumed, there was no
clogging.
COMPARATIVE EXAMPLE 6
The ink of Example 6 was poured into a polyethylene bag having 500
ppm of a fatty acid series stabilizer and a fatty acid series slip
agent and the test described in Example 6 was conducted. Filmy
substances clogged the nylon filter and print quality deteriorated
before 200 cc of ink was consumed. Analysis showed that the filmy
substance was a mixture of erucamide and oleamide which appeared to
be separated from the slip agent on the surface.
EXAMPLE 7
200 cc of ink having the following composition was prepared.
______________________________________ C.I. Direct Black 154 2 wt %
Glycerin 20 wt % Triethylene glycol 5 wt % Potassium hydroxide 1 wt
% Ultrapure water 72 wt %
______________________________________
The ink composition was poured into a polyethylene bag containing
100 ppm of a fatty acid series stabilizer and a fatty acid series
slip agent and was tested as described in Example 6. The filter was
not clogged after 200 cc of ink had been consumed.
COMPARATIVE EXAMPLE 7
200 cc of the ink of Example 7 was poured into a polyethylene bag
containing 200 ppm of a fatty acid series stabilizer and a slip
agent and the test was conducted as described in Example 7. Filmy
matter was clogged in the nylon filter having a pore size of 30
.mu.m before 200 cc of the ink was consumed for printing and print
quality deteriorated. Analysis showed that the primary component of
the filmy matter was sodium stearate. In addition, the sodium
stearate was assumed to be produced by a process wherein the
stabilizer contained in the polyethylene eluted into the ink and
reacted with sodium ions in the dye, C.I. Direct Black 154. As
described, when an ink tank having an ink composition with a sodium
ion concentration between about 0.001 and 0.2% by weight is
maintained at an elevated temperature or for an extended period of
time, fatty acid or fatty acid derivatives eluted into the ink
which contained in the materials of the ink tank do not react with
sodium ions in the ink to produce insoluble substances. In
addition, when an ink tank contained 10 to 100 ppm of fatty acid or
fatty acid derivatives in the tank material is maintained at an
elevated temperature or for an extended period of time with ink,
fatty acid or fatty acid derivatives do not elute into the ink and
separate. As a result, the ink flows stably in the ink supply
system of an ink jet recording apparatus and no deterioration of
print quality or dot missing is observed. As a result, reliability
of the ink jet recording apparatus is improved.
It will thus be seen that the objects set forth above, among those
made apparent from the preceding description, are efficiently
attained and, since certain changes may be made in the above
composition without departing from the spirit and scope of the
invention, it is intended that all matter contained in the above
description shall be interpreted as illustrative and not in a
limiting sense.
It is also to be understood that the following claims are intended
to cover all of the generic and specific features of the invention
herein described and all statements of the scope of the invention
which, as a matter of language, might be said to fall
therebetween.
Particularly it is to be understood that in said claims,
ingredients or compounds recited in the singular are intended to
include compatible mixtures of such ingredients wherever the sense
permits.
* * * * *